The present invention relates to a side airbag apparatus that deploys and inflates an airbag on a side of an occupant.
A typical side airbag apparatus deploys and inflates an airbag on a side of an occupant when an impact having a magnitude not less than a predetermined value is applied to a body side portion of the vehicle due to a collision to the side of the vehicle (side collision), thereby absorbing the impact to protect the thorax or lumbar regions of the occupant. As such a side airbag apparatus, a type has been known that, in consideration of the manner in which a side portion of a vehicle body intrudes into the passenger compartment at a collision, deploys and inflates an airbag that corresponds to an area including a shoulder and the lumbar regions of an occupant (for example, refer to Japanese Laid-Open Patent Publication No. 2004-291789).
Due to recent improvements of the rigidity of lower parts of vehicles, even if an impact of a collision is applied to a side portion of a vehicle body and the magnitude of the collision is not less than a certain value, the lumbar regions of the occupant receive a relatively small impact as compared to the impact applied to the other sections in the area including the shoulder and the lumbar regions. However, the shoulder still receives a considerable impact at a collision. Accordingly, it has been desired that a section of an airbag that corresponds to a shoulder be deployed and inflated prior to the deployment and inflation of the remainder at a side collision.
However, the side airbag apparatus disclosed in Japanese Laid-Open Patent Publication No. 2004-291789 is configured to first deploy and inflate a portion of the airbag that corresponds to the lumbar regions of an occupant. Therefore, taking into consideration the fact that, as described above, a side collision to a recent vehicle causes a side portion the vehicle to intrude into the passenger compartment in a falling manner, the airbag apparatus of the publication still has room for improvement to deploy and inflate a portion of an airbag that corresponds to a shoulder prior to the remainder of the airbag.
When an airbag apparatus is configured to deploy and inflate a portion of an airbag that corresponds to a shoulder prior to the remainder of the airbag, differences in physical sizes of occupants must be taken into consideration. This is because the position of the shoulders greatly vary depending on the physical sizes of occupants. When taking such differences in physical sizes of occupants into consideration, determining a reference physical size to be that of a relatively large occupant causes the following problems. That is, since the position of shoulders of a small occupant is lower than a large occupant, a space can be created between such a small occupant and the body side portion of the vehicle at a collision. It is therefore difficult to restrain the shoulder of a small occupant with the airbag.